Some people used to test the color amount of the four-color machine in the order of color and color inversion. The results are shown in the following table. When the four-color machine is wet and wet, the amount of color of the inverted color sequence is better than that of the color sequence. The amount of overlapping color is reduced by 11.7, and the amount of overlapping colors of the secondary and tertiary colors is lower, which objectively affects the saturation of the color, particularly in the midtones and shadows, and the color rendering effect is poor and the colors are not abundant.
Fourth, the transparency of the ink The ideal ink, which itself should be absolutely transparent, otherwise, in the multi-color printing, the light can not reach the underlying ink layer through the upper ink layer, then the overlay can not show the effect of mixing . The hue, saturation, and lightness of the composite color are severely affected.
From the perspective of the transparency of the four-color inks used today, the black ink is the worst and the clear yellow ink is the best. The magenta and the blue inks depend on the pigments and binders used. The general situation is the ratio of the blue ink to the red ink. Poor ink transparency. When printing, inks with poor transparency are generally printed first, and inks with good transparency have to be printed. Of course, the four-color machine printing sequence usually used now puts the yellow ink on the last color printing. Besides the reason that the yellow ink has high transparency, there are also the following reasons:
1. Widely use the low-absorption coated paper and the practical needs of the four-color machine for rapid printing, which overcomes the wet overprint problem that is caused by the large area of ​​the yellow printing.
2. It avoids the tendency of the blue and black ink to have a bronze luster after the ink is dry. There is no longer a feeling of color impure.
3. Avoid excessive expansion of yellow dot.
V. Overprinting Problems In the design of certain print processes, overprinting problems may be a determinant factor in multicolor printing presses. This factor is mainly for the dimensional stability of the paper. For example, when the middle of a picture is an inverted white text with a black box, and the surrounding is a full-color version, the black bars are just in contact with the full version. At this time, if the paper is very stretched during printing, it may cause overprinting difficulties. Therefore, when arranging the printing color sequence, the black frame should be printed first, and then the printing ink should be printed. This is due to the smaller paper stretch caused by the first printing of the black frame, and it is easier to print the full version over black.
Sixth, double shadow situation Under normal circumstances, the first color of four-color machine printing color sequence is often black. However, some prints, such as product catalogs, often have most of the textual descriptions in the black version. If the substrate is a poor-quality coated paper during printing, the retractable width of each sheet is likely to be different, and the first color of black ink will be partially transferred to different positions on the surface of the second color blanket cylinder. There is a danger of double shadows. Double images can make the text blurry and affect product quality. In this sub-case, black should not be placed in the first color, but it should be more appropriate to put it in tricolor or final printing.
VII. Proofing and proofing is not only the final process of plate making, but also the “first mover†of printing. Proofing plays a role in the quality of plate making and also provides a reliable basis for the printing process.
At present, the platform-type monochrome proofer widely used in proofing is very different from the printing machine in its machine structure, printing method, printing pressure, and operating speed. Therefore, it is difficult to make the quality of printed matter exactly the same as proofs. But as long as we can properly handle the relationship between the proofing and printing process, especially the printing sequence, we can completely reduce the gap between print quality and proofs.
Monochromator printing and four-color printing, the print quality judgment process is consistent. For a monochrome machine, the printing effect can be judged according to the single pattern or the overlapping proofs for each color printed, and the printing method of the monochrome machine is the same as the printing method of the proofer, which belongs to the wet-dry printing method. Therefore, as long as the same print sequence is used, the print quality is easier to control. The four-color printing adopts the wet and wet printing method, and the print is formed once, so the printing effect is far from the proofs. In order to make proofing a more reliable basis for four-color machine printing and to narrow the gap between proofing and printing, the following aspects should be emphasized when proofing:
1. The color sequence of proofing is exactly the same as the color sequence of printing.
2. Use four-color proofer for proofing.
3. Use the same printing plate, paper, and ink as the printing.
VIII. Printing, Printing, Printing, Printing, Printing, Printing, Printing, Printing, and Printing Silver printing is generally performed in the field, with thick ink layers and high process requirements. They are usually printed at the end of the printing. In summary, there are many factors affecting the printing sequence of four-color machines, and even some factors are in conflict with each other. Therefore, we can only take a compromise when determining the printing color sequence.
Many printers generally use a four-color machine to print color sequences black-cyan-magenta-yellow, or black-magenta-cyan-yellow. The two kinds of printing color sequences are determined after combining many factors. They are the two basic color sequences of a four-color machine. Among them, the black-cyan-magenta-yellow color printing sequence is used more often. Called the standard color sequence of a four-color machine. However, this is not the only one. It should be determined according to the specific circumstances when printing. The new situation cannot be applied rigidly. (Finish)